This is a view of a truck loaded with equipment driving across a bridge spanning the Colorado River at Hoover Dam site. Construction workers and equipment are shown on the bank of the river. At the right is...

View of the beginning of Hoover Dam contruction at the bottom of Black Canyon. Various pieces of equipment, trucks, workers, etc. are visible including a crane suspended above the construction site. The view is from downstream.

Construction workers are pouring the first concrete for the foundation of Hoover Dam in the bottom of Black Canyon. Large bucket suspended from a crane is visible as well as the concrete frames for the pour.

View from high above the canyon of the early stages of building the wooden forms for pouring the concrete in the construction of Hoover Dam in Black Canyon. Vehicles and other equipment can be seen as well as hoisting...

View of the construction of the foundations of Hoover Dam on the floor of Black Canyon. Various pieces of machinery can be seen as well as a construction building. The view is taken from high above but several...

This photo shows the construction of the foundation of Hoover Dam on the floor of Black Canyon. Trucks, construction equipment, and cranes can be seen as well as several construction buildings. Photo taken from high above the canyon.

View of the construction of Hoover Dam, looking upstream. Shows concrete forms, various construction buildings, and high scaling equipment. Taken from high above, the Colorado River can be seen above the dam site.

View from on high of Hoover Dam construction, looking upstream. The Colorado River can be seen above the dam. Also shows concrete forms, a train winding along the side of the canyon, high scaling equipment, construction buildings, and...

Overhead view of the construction of Hoover Dam in Black Canyon. Looking upstream, the Colorado River is visible above the dam site. Also shows concrete forms, a train winding along the side of the canyon, and various construction...

Construction site of Hoover Dam in Black Canyon, looking upstream. Above the site is the Colorado River. Shows concrete forms, a train winding along the wall of the canyon, various construction buildings, hoisting machinery, and a cable suspended...

View of Hoover Dam construction site, looking upstream. Above the site is the Colorado River. There are concrete forms, construction buildings, hoisting machinery, and a cable high above the Black Canyon in the picture. There is also...

Construction photo of Hoover Dam in Black Canyon, showing the Colorado River above the dam site. Also shows concrete forms, a train winding along the canyon wall, high scaling and hoisting machinery, various construction buildings and a cable suspended...

Overhead view of the construction of Hoover Dam in Black Canyon with the Colorado River visible above the dam site. In the photo are concrete forms, various construction buildings, a train winding along the side of the canyon, high...

View of Hoover Dam in the later stages of construction. The Colorado River can be seen above the dam. The intake towers now rise behind the dam and this view also shows concrete forms, hoisting equipment and...